• 3.8 baseline — 0.6 × season 3.8 (4 gm) + 0.4 × last 4 3.8
• −0.4 opponent leak — they concede 50.3/game vs a 56.6 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission.